Chapter 11

NCERT
Class 9
Science
Solutions
10. When a sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound production remains the same. Do you hear echo sound on a hotter day?

Question:

When a sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound production remains the same. Do you hear echo sound on a hotter day?

Answer:

∴ Time = Distance / Speed (velocity)

that is, time and velocity (speed) have an inverse ratio. Increasing the temperature of any medium increases the speed of sound. Therefore, on a hot day, due to the higher temperature, the speed of sound will increase and we will hear the echo sooner than the cold days.

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